Mental health hospitals are some of the least healthy places I've ever seen. No fresh air, no ability to exercise, no activities, no mental stimulation, shit food. Discharged physically ill, unfit, overweight, addicted and traumatised. I had friends go into hospital non-smokers and come out addicted because the only activity and place to socialise was the smoking room. Never mind the PTSD they acquired In hospital. Really fucking helpful.
Good on you for trying to find a way to do something about that national disgrace. Genuinely, what a refreshing thing to read.
How much scope would there be to involve service users in developing these plans and running it / making decisions?
I think it would be really important - as far as possible - that it be something run/developed by them not yet another thing done to them or imposed on them that they have no influence in or say over. Co-production and all that.
Your perception (and staff perceptions) of what is important, how they would benefit etc will be different from those of service users. There is such a huge power differential between staff and service users, so I would be very mindful of not taking more power away from people.
I can't think of any practical advice right now, but on a more personal level please don't get disheartened if people are jaded or unenthusiastic. I hope you won't give up on the idea of making a positive difference. Even if the idea you have now develops into something a bit different or doesn't reach as many people as you're hoping.
Locally I've seen some really brave and innovative projects finally start to get off the ground, so it can happen when people like you come along and are prepared to plug away until they get the model right and make the right connections to make things happen. It's so worth it.
Good luck.